import requests
def get_wall(message):
    unsplash_url = "https://source.unsplash.com/3840x2160/?"

    if len(message.split()) > 2:
        search_terms = message.split()[1:]

        # Turn search_terms into strings separated by commas
        joined_terms = ','.join(search_terms)

        # Add those comma separated strings onto the end of the URL variable
        url = unsplash_url + joined_terms

    elif len(message.split()) > 1:
        term = message.split()[1]
        url = unsplash_url + term

    else:
        url = unsplash_url

    response = requests.get(url).url

    if 'photo-1446704477871-62a4972035cd' in response:
        return "Could not find an image for those tags."
    else:
        return response